Blepharitis and Dry Eye

Blepharitis means inflammation of the eyelids, particularly around the eyelid margins. The eyelid margin is a busy anatomical area. It contains:

• •the eyelashes and their follicles
• •the openings of the meibomian glands
• •sebaceous glands associated with the eyelashes

It also includes tissue that comes into close contact with the tear film every time you blink. Problems in this area can therefore affect much more than the skin of the eyelid. They can influence the meibomian glands, blinking, tear-film composition and the ocular surface.

Traditionally, blepharitis has often been divided into two broad categories.

Anterior blepharitis

Anterior blepharitis primarily affects the front part of the eyelid margin, around the eyelashes and their follicles. It may be associated with bacterial overgrowth, seborrheic disease, Demodex mites or other inflammatory processes.

Posterior blepharitis

Posterior blepharitis affects the back part of the eyelid margin, particularly the area associated with the meibomian glands. Historically, the term has often been used in connection with meibomian gland dysfunction (MGD). But the terminology can become confusing because MGD is not simply another name for blepharitis.

MGD specifically describes abnormalities of meibomian gland function, while blepharitis describes inflammatory disease of the eyelid margin. The two can overlap.

No. This distinction is important. Blepharitis describes inflammation involving the eyelid margin. MGD describes dysfunction of the meibomian glands.

A person can have both. Inflammation around the eyelid margin can potentially interfere with meibomian gland openings and function. And abnormalities of meibomian secretion can themselves be associated with changes and inflammation at the lid margin. So the relationship may run in more than one direction.

This is why it is usually too simplistic to say:

“Blepharitis causes MGD.”

In some patients, blepharitis may contribute to meibomian gland dysfunction. In others, MGD may be the dominant eyelid problem. And in many people, several processes coexist.

Meibomian Gland Dysfunction (MGD): what actually happens inside the glands — coming soon

There is no single pathway. Depending on the type of blepharitis and the individual patient, several mechanisms may be involved. Inflammation and debris around the eyelid margin can alter the environment where the tear film meets the eyelids. If the meibomian glands are also affected, the amount, quality or delivery of meibum may change.

That can contribute to abnormalities in the lipid component of the tear film. Eyelid-margin inflammation may also contribute directly to irritation and ocular-surface inflammation. And because the eyelids interact with the tear film during every blink, abnormalities of the lid margin can influence the overall stability of the ocular surface.

So the pathway may involve:

eyelid-margin disease→gland and/or tear-film disturbance→loss of ocular-surface homeostasis

But the exact pathway will not be identical in every patient.

No. This is another important distinction. TFOS DEWS III specifically notes that people with anterior blepharitis do not necessarily have dry eye disease. Some may even be asymptomatic.

For blepharitis to be clinically important in a dry-eye evaluation, we need to look at the larger picture:

• •Is the tear film unstable?
• •Is there ocular-surface damage?
• •Are the meibomian glands affected?
• •Is there inflammation?
• •What symptoms does the person have?

And does the eyelid disease appear to be contributing meaningfully to those findings? Simply seeing some debris around the eyelashes does not automatically explain every dry-eye symptom.

There is no single cause. Different forms of blepharitis may involve different mechanisms, including:

• •bacterial changes around the eyelid margin
• •seborrheic skin disease
• •Demodex mites
• •rosacea
• •meibomian gland dysfunction
• •other inflammatory changes of the eyelid margin

Several of these conditions can occur together. This is why “blepharitis” can sometimes function more like an umbrella clinical description than an explanation of the underlying cause. The useful next question is therefore: why is this person’s eyelid margin inflamed?

Demodex mites naturally live in human skin and hair follicles, and their prevalence increases with age. But in some people they are associated with Demodex blepharitis. One particularly characteristic sign is the presence of collarettes: cylindrical debris around the base of the eyelashes. Modern reviews consider collarettes a key diagnostic sign of Demodex blepharitis.

Demodex can contribute to inflammation through several proposed mechanisms, including mechanical irritation and inflammatory responses. It has also been associated with MGD, ocular rosacea and dry-eye symptoms. But because Demodex deserves its own explanation, we will cover it separately rather than treating every case of blepharitis as Demodex disease.

Demodex and Dry Eye: when eyelid mites become part of the problem

Rosacea can involve more than facial skin. When it affects the eyes and eyelids, it can be associated with:

• •eyelid-margin inflammation
• •telangiectatic blood vessels
• •MGD
• •ocular-surface inflammation
• •dry-eye symptoms

TFOS DEWS III includes ocular rosacea among eyelid disorders that can produce or contribute to dry-eye-like symptoms. Again, this demonstrates why blepharitis should not always be treated as the final diagnosis. Sometimes it is part of a larger condition.

Ocular Rosacea and Dry Eye: how rosacea can affect the eyelids and ocular surface

Symptoms vary considerably. They can include:

• •burning
• •itching
• •grittiness or foreign-body sensation
• •red or irritated eyelids
• •crusting or debris around the eyelashes
• •watery eyes
• •dry-eye-like discomfort

But symptoms alone cannot tell us which type of blepharitis is present, or whether blepharitis is actually responsible for the symptoms. Many of these sensations overlap with dry eye and other ocular-surface conditions.

Conditions That Look Like Dry Eye

Diagnosis usually begins with examination of the eyelids and eyelid margins. A clinician may look for:

• •redness or swelling
• •debris or crusting around the eyelashes
• •collarettes
• •changes in the eyelashes
• •telangiectatic vessels
• •abnormalities around the meibomian gland openings
• •other signs of lid-margin disease

The rest of the ocular surface should also be examined. That matters because the clinically useful question is not simply “Is blepharitis present?” It is: what kind of eyelid disease is present, what may be causing it, and is it contributing to the patient’s ocular-surface problem?

How Dry Eye Is Diagnosed

Often, yes. Because eyelid-margin disease and MGD frequently coexist, examining the meibomian glands can help determine whether gland dysfunction is part of the picture. As we discussed in the diagnostic section, this may involve looking at:

• •gland expressibility
• •meibum quality
• •gland openings
• •and sometimes meibography or lipid-layer assessment

The goal is not simply to collect more abnormal findings. It is to understand whether the glands are actually involved.

Meibography: imaging the glands

Sometimes treating an important eyelid contributor can improve the overall ocular-surface picture.

But it is not guaranteed to resolve dry eye completely. A person may simultaneously have:

• •MGD
• •aqueous deficiency
• •tear-film instability
• •exposure
• •ocular-surface inflammation
• •neural abnormalities
• •or other dry-eye drivers

So treating blepharitis addresses one identified contributor. Whether that is enough depends on the individual dry-eye system.

Dry Eye Is Often Mixed

Eyelid hygiene is commonly used in blepharitis management, and TFOS DEWS III includes lid-hygiene approaches among management strategies for eyelid-related disease. But treatment should ideally depend on what is causing the blepharitis. Demodex blepharitis, for example, may require targeted anti-Demodex treatment rather than simply being treated as nonspecific eyelid inflammation. Randomized-trial evidence now supports targeted lotilaner treatment for Demodex blepharitis, illustrating why identifying the underlying form matters.

Likewise, rosacea-associated eyelid disease may require a different strategy. So “you have blepharitis” should ideally be the beginning of the explanation, not the end.

Treating Meibomian Gland Dysfunction